Programme switch



Nov. 24, 1959 A, WEBER 2,913,913

PROGRAMME SWITCH Filed Aug. 6, 1957' {Sheets-Sheet 1 I INVEJNTOR.

Artur Weber Nov. 24, 1959 A. WEBER 2,913,913

PROGRAMME SWITCH Filed Aug. 6, 1957 s Sheets-Sheet 2 J INVENTOR.

Artur Weber NOV. 24, 1959 E R 2,913,913

" PROGRAMME SWITCH Filed Aug. 6, 1957 I I 3 Sheets-Sheet 3 INVENTOR.

flrrur Weber (fwd/E a substantial disadvantages.

United States Patent 9 "ice 2,913,913 PROGRAMME SWITCH Artur Wcber,.Muri, near Bern, Switzerland, assigiior to Saia A.G., Murten, Switzerland Application August 6, 1957, Serial No. 67 6,588-

Claims priority, application Switzerland October 18, I956 11 Claims, (Cl. 74-125) ing cycles in machines, especially washing machines.

Thus, it is often desired to vary the course of the programme, for which purpose the control members are disengaged from their actuating means and brought into the position required, from which the programme is to take its course.

The working programme of washing machines normally extends over a considerable period of time of, for example, one hour or more, thus it is necessary for the control elements, e.g. the cam discs controlling the switch contacts, to be driven at a very slow speed. Therefore it is necessary to incorporate a correspondingly dimensioned gearing between the control elements and their driving means, for example a synchronous motor. Besides, in known programme switches, a disengageable clutch has been provided between the gearing and the control elements, which entailed various Above all the clutch between the driven Wheel of the gearing and the cam discs takes up considerable space. Besides, it was necessary for the clutch to be constructed in such a manner that it was rigidly engageable with very many relative positions of its halves, in order to render possible finely stepped adjustments of the cam discs or other control elements with the driven wheel of the gear being stationary. This demand necessitated acomparatively costly structure of the clutch and taking up considerable space.

In order to traverse these difficulties it has also been proposed to provide between the driving means, eg the :synchronous motor and the control elements, a worm gear, in which the worm is adapted to be laterally disengaged, in order to attain a disengagement of the control elements from the driving means for the purpose of obtaining any displacement thereof. This arrangement, however, has various substantial disadvantages. By way of such aworm gear, the cam discs for the control of the contacts are continuously driven, 'which causes a very slow and indefinite closing and opening of the controlled contacts or circuits respectively, and thus results in inaccurate control and considerable sparking at the contact. It is, therefore, generally desired to actuate the control means step by step, in order to obtain rapid and clear contact control. It is often difficult to re-engage the worm wheel.

The present invention combines the advantages of the known programme switches whilst avoiding the disadvantages thereof. Broadly the invention relates to a programme switch with control elements, for example cam discs or the like, acting on switch contacts, wherein the control elements can be disengaged from driving means for the same, and can be brought into any dev 2,913,913 Patented Nov. 24, 1959 siredcondition, comprising a stepped. switch gearing having a. step switch. gear wheel and a forward. switch pawlv operatively associated with the said stepswitch: gear wheel for stepwise advancing it, theisaid stepped: switch gearing. beng arranged between the said driving. means and the said ,control elements; and the said step switch gear wheel. being rigidly connected with the said control elements, stop means, and a rest condition. for the said. forwardswitch pawl: for which the forward switch pawlengages the said stopwmeans and blocks the:

step switch gear wheel against forward rotation, manual-ly operable means independent ofthe said: driving; means for retracting the said forwardswitch pawl from its rest conditionto a positionin which the pawl is disengaged from thesaid stop means. and for which disengag'ed position the pawl permits a forward rotation of the step switch gear. wheel- One and the same pawl.

also serves to continue switching the control elements? step: by step, for? example the camdiscs and thus renders possible clear and defined switching stages, and. the:

control elements to be locked against rotation in: the:

forward direction anddis'engagement of the control elements. from their driving means for turning the control elements by any. degree. The programme switch: in.

accordance with the invention is, therefore, distinguished.

by being particularly simple, as a step switching pawl on the one hand allows the switch to operate reliably" Figs. 3' to 5 show a second embodiment of the pro gramme switch in elevation from the inside, from the outside or in sectiontaken on the line VV of Fig; 4',

Fig. 6 shows a third embodiment of the programme switch, and

Fig. 7 is asection through a set of terminals of the programme switch taken on the line; VIIVII of Fig. 6.

The programme switch shown in Figs. 1 and 2 has a. chassis comprisihgtwoplates 1 and 2, which are preferabl-y moulded from plastic material and which are connected by means of bolts 3 and 4. In co-aXial bores of the plates 1 and 2 there is mc unt'ed a shaft 5 at an outwardly projecting end thereof, which carries an operating knob 6 with a scale disc 7. Mounted on the shaft 5 between the plates 1 and 2, there is a control cam disc 8 in such a way that the shafts may be axially displaced in the boss of the cam control disc 8, but not turned therein. The cam disc 8 has a toothed edge and co.- operates with a step pawl in a manner described later on in the shape of a ratchet wheel. Between the boss of the cam disc 8 and the plate 2, there is disposed a lever 9, which is pivotally mounted about a pin 10 fixed on the plate 2, and which with a control surface 11 projects into the region of, a conical shoulder or control sun face '12 of the shaft 5. A tension spring 13 engages at the extreme end of the lever 9 and tends to swing the lever 9 constantly anti-clockwise in Fig. 2, whereby a pawl 15 pivotally mounted at 14 on the lever 9 and kept in, constant engagement with the toothing of the cam disc 8 by means of a tension spring 16, is wedged between the pin4 and the cam disc and consequently prevents the cam disc from being rotated.

A switch disc 17 having an engaging pin 18 is pivotally mounted in the region of the extreme end of the lever 9 mounted in 'an eyelet of the plate 1. A crank 19 on which engages a tension. spring 20, is connected with the switch disc 17 on the outside of the plate 1. The switch disc 17 has a boss 21, which at the free end has a semicylindrical milled portion 22. In a bore of the boss 21 there is a shaft 23, mounted so as to be freely rotatable, which is also mounted in the plate 2 and which carries a driving gear wheel 24 outside the plate 2. In the region of the semi-cylindrical milled portion 22 of the boss 21 there is inserted in the shaft 23 a pin 25 projecting on one side which, with the milled portion 22, from a free-wheel clutch, in that it is adapted to engage the boss in one direction, and then allows same to turn freely practically through half a turn in the same direction. The gear wheel 24 and consequently the shaft 23 is driven by a synchronous motor 26, only partly shown in the drawing, by way of a further gear wheel 27 at a speed of, for example, a revolution per minute, when the programme switch is in operation.

Mounted .on the same shaft as the gear wheel 27 there is a cam body 28 of insulating material which controls two contact laminae 29 and 30, in such a manner that one of each alternatively, during approximately half a minute, makes with a common contact 31, while the other one is disconnected. These switch contacts serve, for example, to change-over the driving motor for the washing drum of a washing machine.

The shaft is provided with two peripheral grooves 32 and 33, in which a spring. stirrup 34 held between the cam disc 3 and the plate 1 is adapted to engage and thus determines two axial operating positions of the shaft 5, depending upon whether it is located in the inner groove 32 or in the outer groove 33. The cam disc 8 is secured against axial displacement on the one hand by the spring stirrup 34 and on the other hand by the boss thereof abutting against the lever 9, so that when the shaft 5 is displaced from one operational position to the other, the cam disc 8 cannot be axially displaced. One of the pins 3 or small distance tube slid thereon serves as the mounting for a plate spring 35, which by means of two flaps, offset through half a pitch of a tooth, engages in the toothing of the cam disc 8 and prevents the latter from being turned in the reverse direction.

A pointer 36 is mounted with frictional connection on the brss of the actuating knob 6, so that normally this pointer is carried along with the scale 7 and the actuating knob 6, but by overcoming the friction, it may be turned relative to these. parts so as to allow the pointer to be positioned at any required point of the scale 7. The pointer 36 has a control arm 37 with a control projection 38, in whose path there projects a control cam 39 of a control lever 41 of insulating material pivotally mounted on a pin 40. The control lever 41 has a shoulder 42, which in a manner described later on, is adapted to co-operate with a control disc 43 mounted on the shaft 5.

A U-shaped metal frame 44 is secured by means of the two plates 1 and 2 not shown in detail in the drawing. The shanks of the frame 44 are provided with punched out portions 45 and the yoke of the frame is screwed on to an insulating body 46, which engages between the two plates 1 and is anchored between them by' means of a bolt 47. A terminal block 48 or 49 respectively, is screwed to each shank of the frame 44. The terminal blocks 48 and 49 each comprise a partof moulded material having a base plate 50 and upright ribs 51 at a right angle thereto, which ribs act as insulating partitions between compartments, in which contact laminae 52 are arranged pivotally about pins 53. The ribs 51 project at one side beyond the base plate, so that the inwardly bent free ends of the contact laminae 52 can project inwardly towards the cam disc 8 in order to co-operate with control cams 8' mounted on. the lateral faces of the cam disc 8. The ends of the ribs 51 not connected with the base plate 50 are inter-connected by webs 54, in order to reinforce the ends of the ribs and to protect them from breaking off. Each contact lamina 52 is provided with an outwardly projecting pin 55 on which engage tension springs 57 anchored on further webs connecting the ribs 51 and which tend to swing the contact laminae 52 inwardly, thus tending to urge the free ends thereof against the cam disc 8, or the contact members 58 thereof against contact elements 59 on the shanks of the frame 44. The bearing pins 53 of the contact laminae 52 are carried by laminae 60, which together with terminals 61 are screwed to small plates which are inserted from the rear in the base plate. Between the contact laminae 52 and the fixing laminae thereof it is possible for flexible plate springs or braids, not shown in the drawing, to be fitted, which ensure a reliable conducting connection between the parts 52 and 60.

On one of the contact strips (lamina) 52 of the terminal block 49, preferably on the innermost lamina 52, there is inserted a pin 63, which in a manner as evident from Fig. 1, engages behind a projection 64 of the control lever 41. This contact lamina 52' is connected to the live phase of the control circuit of the programme switch.

The programme switch shown in the drawings operatesv as follows: i

The operational position shown of the programme switch corresponds to the period half way through the programme. The synchronous motor, which is fed via the contact lamina 52' which in this operational position is in contact with the metal frame 44, is running and drives the gear wheels 27 and 24 at a speed of, for example, one revolution per minute, viz in such a direction that the shaft 23 with the pin 25 in Fig. 2 rotates anticlockwise. In the position shown on the drawing, therefore, it is still possible for the pin 25 to execute in the milled flat 22 of the boss 21 approximately a third turn in this direction and until it strikes the left-hand surface of the milled flat, at which instant it engages the boss 21 and the parts 17, 18 and 19 connected therewith. Consequently, the crank 19, which up to now was held in the position shown in Fig. 2 determined only by the tension of the spring 20, is twisted together with the shaft 23 anti-clockwise, whereby the spring 20 is tensioned. If the parts 17, 18 and 19 are displaced from the position as shown in Fig. 2 through then the crank 19 arrives at its upper dead centre, and shortly after passing same is turned on rapidly by the spring 20 anti-clockwise (Fig. 2) again into the inoperative or rest position shown in the drawing. The pin 25 thereby leaves one of the surfaces of the milled flat 22 and allows the boss 21 to be freely rotated and the parts connected thereto through about 180 into the original position as illustrated. During this movement, the engaging pin 18 strikes against the lower edge of the free end of the lever 9 and lifts same against the pull of the spring 13 to such an extent upwards that the pawl 19 leaves range of the pin 4 and is set back in the toothing of the cam disc 8 by more than the pitch of a tooth. The lever 9, subjected to the pull of the spring 13, drops back into the position illustrated as soon as the switch pin 18 has left it, whereby the pawl 15 advances the cam disc 8 through one pitch of the toothing and due to the wedging between the pin 4 and the cam disc instantly prevents a further rotation thereof. The switching movement due to being actuated by means of a suddenly discharged storage force takes place extremely rapidly, thus practically excluding an involuntary turning of the cam disc during the temporary removal of the pawl 15, from its clamping position. In this manner the cam disc 8 turned further step by step, whereby the contact laminae 52 are actuated by the control cams 8' of the cam disc 8, in order to control the individual parts of the machine. Mounted in the boss of the cam disc 8 there is a pin or key engaging in a keyway of the shaft 5, thus causing the shaft 5 and the cam disc constantly to be turned rigidly one with the other. Therefore, in particular also the actuating knob 6 with the pointer 36, the control arm 37 and the control projection 38 are carried along during i hing cycle of the programme switch.

At the end of the programme the control projection 38 strikes from below in Fig. 1 the control 39 of the switch lever 41, thus causing the switch lever '41 .to .be turned, and with thepro'jection 64 thereof turns the pin '63 and thus the lamina 52' outwards into the open position, whereby the supply of current via the contact 52 to the metal frame 44, which presents the common pole of all control switches and to which the synchronous motor 26 is connected, to be disconnected. With this, the programme switch and all parts of the machine supervised thereby are switched off, thus terminating the working cycle.

If the programme switch is to be operated to control a further working cycle, then it is necessary for the actuating knob 6 and the cam disc 8 with the control arm 37, 38 to be advanced to such an extent that the projection 38 leaves the projection 39 and consequently in turn allows the contact lamina 52 to close. Since, however, the pawl 15 prevents any forward rotary movement and the pawl 35 any reverse rotary movement of the cam disc by means of the actuating knob 6, it is necessary first of all to ensure the pawl is disengaged from the cam disc. For this purpose the actuating knob 6 with the shaft 5 is pressed inwards into the internalaxial position determined by the groove 33 of the shaft 5. During this inward movement of the shaft 5 the conical surface 12 of the shaft 5 strikes against the control edge 11 of the lever'9 and turns same clockwise against the pull of the spring 13, thus causing the pawl 15 to be moved out of range of the pin 4, and thus allows the cam disc 8 to beturned in the usual direction, thus forwardly by any amount. With this, it is possible for the actuating knob with the parts connected therewith to be turned into a starting position, till the projections 38 and 39 have been moved out of contact with one another. When depressing the shaft 5 into its inner operational position, however, the control disc 43 of the shaft 5 has seized the shoulder 42 of the control lever 41 and further retained in the switched olf position in which the contact 52' is open. On attaining the starting position, the shaft 5 is again pulled into the outer operational position, whereby the control disc 43 release the control lever 42 and with that the contact lamina 52'. Consequently, the metal frame 44 is energised again, the synchronous motor 26 starts up and drives the cam disc 8 by way of the pawl 15 which is also engaged again, in the manner mentioned above, in order to control a further working cycle by means of the contacts 52.

If, for example, itis desired to terminate this working cycle earlier than normally, thus allow only a part of the programme to be completed, then the pointer 36 and the control arm 37 therewith is turned from the end position at which it generally is situated, to the point of scale which determines the moment at which the programme is to be terminated. The control projection 38 will, therefore, already strike against the control cam 39 and stops the programme switch in the described manner as soon as the programme has been carried out up to the position indicated by the position of the pointer.

If it is not desired to start the programme at the usual starting point, then the actuating knob and the scale 7 rigidly connected thereto are turned to the point at which the programme is to be started instead of to the usual starting point.

If a part of the programme is to be omitted at any point, then the actuating knob with the shaft 5 is pressed in as soon as the scale on being rotated has reached the position which corresponds to the moment at which the operation is to be interrupted. Thus the programme switch and the machine controlled thereby are stopped in the manner described. It is now possible to turn the scale into the position corresponding to the position of the working programme in which the operation is to be resumed. Then the actuating knob 6 is pulled outwards again and 6 the programme switch continues to tion attained.

Any part of the programme may be repeated in an absolutely similar manner in that the unlatched cam disc 8 is turned forwards beyond zero position into a position corresponding to a point of the programme further back on the dial.

Figures 3 to 5 illustrate a different embodiment of the step switch mechanism of the programme switch in accordance with the invention, in which corresponding parts are denoted by the same reference numerals as in the Figures 1 and 2. The cam shaft 5 is mounted by means of a boss 65 in the plate 66, shown in the drawing, of the switch chassis and can also be brought into two axial positions, which are determined by the engaging of a lever 68 subjected to the action of a spring 67 in a deep groove 69 or a more shallow groove 70. The lever 68 is mounted at 71 pivotally on the plate 66 and on its movable end has an elongated hole 72 in which engages a pin 73 projecting through a slot of the plate 66. The pin 73 is fixed on the movable end of step switching lever 9 pivotally mounted on the boss 65. On the step switch pawl 15 pivotally mounted on the step switch lever there engages a tension spring 74 which urges the pawl 15 upwards against the fixed pin 4 and consequently into the toothing of the step switch wheel 8 and at the same time holds the lever 9 in the upper rest position shown in the drawings.

A cam disc 75 is mounted so as to be loosely rotatable on the drive shaft 23, which herein rotates clockwise. This cam disc 75 has a spiral-like rising curved portion 75 and a rectilinear, steeply sloped curved portion 75", and is provided with an engaging pin 76 which projects into the path of a pin 25 of the drive shaft 23. Furthermore, the cam disc 75 is fitted with a switch pin 18 which when the cam disc is rotated is adapted to engage the end of the switch lever. Bearing on the cam disc 75 there is a roller 78 mounted on a lever 77, thus allowing the lever 77 mounted on a pin 79 to be swung constantly into the position subjected to the pull of a spring 80 determined by the abutment of the roller 78 against the cam disc 75. On the pin 78 there is also mounted a spring-loaded pawl 81, which prevents any reverse turning of the ratchet wheel 8.

As with the programme switch according to Figs. 1 and 2, the drive shaft of that shown in Figs. 3 to 5 is also driven at a comparatively low speed of, for example, one revolution per minute. In the state shown in the drawing, the roller 78 has just made contact with the gradually rising curve part 75 of the cam disc 75, whichdue to the positive engagement between the pins 25 and 76 is rotated clockwise together with the shaft 23. The lever 77 is thus raised further and the spring 80 tensioned until the highest point of the cam disc between the curve parts 75' and 75" arrives underneath the roller 78. Shortly after passing beyond this point, the roller '78 under the tension of the spring 80 slides rapidly along the curve part 75" inwardly and drives the freely rotatable cam disc rapidly further, whereby the engaging pin 76 thereof is lifted oif the pin 25 of the shaft 23. During this rapid movement of the cam disc 75, the switch pin 18 thereof strikes from above against the movable end of the lever 9 and rapidly urges same downwards, whereby the pin thereof moves downwards in the slot 72 of the lever 68 and thus does not engage the lever 68. Due to the downwards movement of the lever 9 the pawl 15 is shifted back by more than the pitch of a tooth, and after releasing the lever 9 it. is rapidly raised again under the tension of the spring, 74, whereby the ratchet wheel is advanced by one stepand immediately latched again. The lever 77 with the spring 80 thus presents a force storage means, which when discharged advances the switch gear wheel 8 by one step.

If the shaft 5 from the position illustrated is pressed.

operate from the posi- 7 inwardly, then the lever 68 is urged downwards by the external conical surface of the groove 69 and then during the subsequent engagement in the groove 70, it rises again by a small degree. Thus, on the whole the lever 68 is subjected to a downwards swinging movement which is transmitted via the pin 73 to the switch lever 9, which is swung downwards to such an extent that the pawl 15 now allows the switch wheel 8 and the cam discs connected .thereto to be advanced. By pulling out the shaft it is possible for the pawl to be re-engaged and the switch gear wheel to be locked. The programme switch shown in Figs. 3 to 5 has exactly the same operational characteristics as the switch illustrated in Figs. 1 and 2.

The programme switch illustrated in Fig. 6 is assembled in a similar manner as the one shown in Figs. 1 and 2. The chassis, however, in this case is formed by means of two interconnected metal plates 1 and 2 in which the movable switch parts are mounted and on which at four points sets of control contacts may be fitted.

The drive of the cam disc 8 is also effected by way of a free-wheel clutch, not shown in the drawing, and a springloaded crank drive 19, 20. On releasing the power storage means formed by the crank drive, a drive cam 100 gets into the region of a pin 101 fixed on the switch lever 9, whereby the switch lever with the shifting pawl 15 is urged downwards against the action of the spring 74 and then by continuing the displacement of the cam disc 8, is raised again by the spring 74.

The shaft of the cam disc 8 is also axially displaceable in two positions determined by the engaging grooves 32 and 33, whereby the switch lever 9 for the inner axial position of the shaft 5 is swung anticlockwise by means of the conical shoulder 12 and by this means it is rendered possible for the cam disc to be shifted in a forwardly direction.

On the side of the actuating knob not shown on the drawing a stop disc 102 having a stop projection 103 is rotatably held. The stop disc is normally held by means of a spring 104 against a fixed stop, not shown, in a position twisted anti-clockwise relative to'the position shown. Let into the shaft 5 there is a pin 105 projecting on one side, which for the inner axial position when the shaft is rotated, strikes against the stop projection 103 and engages the stop disc against the action of the spring 104, and carries it along into the position shown in Fig. 6, in which the stop disc with a stop surface strikes against a stop 106 screwed to the plate 1.

With this, the shaft 5 is prevented from further rotation in a clockwise direction, and the position assumed by the shaft 5 or the cam disc 8 respectively corresponds to the initial position of the cam disc.

The contact terminals are accommodated in insulating bodies 112 which are fitted with two symmetrical flanges -113. By means of these symmetrical flanges 113 it is pression spring 118 which tends to urge the contact spring 114 into the position shown in Fig. 7, in which it is in contact with a counter contact 119. If necessary it is upon whether the actuating tongue 122 stamped out of the contact spring 114 abuts against the unraised end face 8a, the level 8b or the level 80 of the cam disc 8, the contact spring 114 is caused to make contact with the lower counter contact 119, between the counter contacts 119 and 121 or on the counter contact 121. This arrangement allows for a comparatively varied pr0- gramme to be controlled by means of a single track on the cam disc 8 or the available tracks respectively on the cam disc can be very well utilized.

As on the one hand all the insulating bodies 112 are of identical construction and fitted on any point of the switch, and on the other hand the sets of contacts on the one side are not actuated by the same tracks of the cam disc, it is necessary for the shaft 5 to be slightly off centre relative to the plates 1 and 2. In Fig. 8 it is seen that the shaft 5 is located slightly off centre in a downward direction, thus causing the upper sets of contacts to be actuated by the outermost and third track and below by the second and fourth track from the outside.

The programme switch illustrated in Fig. 6 operates in a manner similar to that of those previously described. When the shaft 5 is pressed inwardly into its inner position the pawl 15 is disengaged in the manner described and allows the cam disc to be turned forwardly into any desired operational position. This forward turning motion, however, is limited by the stop projection 103, so that the cam disc can only be rotated to the original I position according to Fig. 6. Thus, if the shaft 5 is pulled possible for an additional contact carrier 120 to be mounted on the insulating body, the opposite contacts 121 of which are disposed above the contact piece of the contact spring 114. If this additional set of contacts 120, 121 is fitted, then it is possible for the control curve of the cam disc 8 shown diagrammatically in development in Fig. 7 to have three different levels. Depending outwardly, then the pin is caused to leave the stop projection 103 and allows the stop disc 102 to be returned anti-clockwise in Fig. 6, thus causing the stop projection to assume a position to the left of the pin 105 in Fig. 6. Thereby projection 103 is rendered ineffective, thus allowing the new programme to start operating immediately.

The step switching mechanisms shown have an important advantage that the pawl serves as a driving member and at the same time as a locking member for the cam disc. A substantial advantage of the switch illustrated herein consists in that all control cams are mounted on one cam disc, which at the same time is provided with a toothing for the drive thereof. By this means there is obtained a particularly narrow compact shape of the programme switch. Due to the fact that the cam disc itself is provided with a toothed edge for its own drive, both the lateral surfaces thereof are free for fitting control cams, which in turn allows an advantageous and space saving arrangement of the sets of contacts. The cam ridges for very accurate control may be fitted on the outside of the cam disc near the edge, where the control path and consequently the accuracy of control is comparatively great. The cam disc may be manufactured in a simple manner in one piece.

Of course, it is possible for the disengagement of the pawl of the cam disc to be effected in a different manner than by axial displacement of the whole shaft 5. It would be possible, for example, to provide a push-button which is independent of the actuating knob 6 and the shaft 5, whereby the lever 9 with the pawl 15, by means of depressing this button, can be disengaged from this locking position, as illustrated, in order to set the cam disc 8 into a required position. Such a switch would be of a somewhat simpler construction, but somewhat more complicated with regard to the operation thereof.

What I claim is:

l. A programme switch with control elements, for example cam discs or the like, acting on switch contacts, wherein the control elements can be disengaged from driving means for the same, and can be brought into any desired condition, comprising a stepped switch gearing having a step switch gear wheel and a forward switch pawl operatively associated with the said step switch gear wheel for stepwise advancing it, the said stepped switch gearing being arranged between the said driving means and the said control elements and the said step switch gear wheel being rigidly connected with the said control elements, stop means, and a rest condition for the said forward switch pawl for which the forward switch pawl engages the said stop means and blocks the step switch gear wheel against forward rotation, manually operable means independent of the said driving means for retracting the said forward switch pawl from its rest condition to a position in which the pawl is disengaged from the said step means and for which disengaged position the pawl permits a forward rotation of the step switch gear wheel.

2. A programme switch according to claim 1, the driving means comprising a lost motion device and a springloaded crank having two dead center conditions, whereby the st motion device permits a free rotation of the crank out of one into another dead center condition.

3. A programme switch according to claim 2, a switching element being connected with the said crank which, on the lost motion of the spring-loaded crank, removes the said lever temporarily from its rest condition to its said disengaged operating condition and thereby actuates the forward switch pawl.

4. A programme switch according to claim 1, comprising a pivotable lever carrying the said forward switch pawl and an axially displaceable shaft carrying at least one cam disc and having a control surface, adapted to operatively engage the said lever on axial displacement of the shaft in one direction, the said lever being pivoted and the forward switch pawl being thereby retracted out of its rest condition.

5. A programme switch according to claim 3, the said driving means having a cam disc driven by way of a lost motion device, on which cam disc a spring-loaded element acts in such a way that it can drive the cam disc in the lost motion direction, wherein the cam disc is provided with a switch element actuating the forward switch pawl.

6. A programme switch, comprising a cam disc acting in axial direction by means of control notches provided at both side faces along circular tracks, for the control of contacts, the cam disc being mounted between two plates, beyond which it projects out radially and that the contacts are arranged in symmetrically constructed contact carriers, which are attachable, in desired positions, to the plate edges laterally of the cam disc.

7. A programme switch according to claim 6, the contact carriers having two symmetrically disposed attachment flanges, by means of which they can be fixed to the plate in any desired condition.

8. A programme switch according to claim 6, comprising change-over contacts, the cam tracks of the cam disc having three different levels, in such a way that the change-over contacts can be brought into two oppositely disposed switching positions and a neutral, open middle position according to which level of the cam track operatively engages the change-over contact associated with it.

9. A programme switch according to claim 6, the axle of the cam disc being displaced from the center of the plate in such a way that tracks of the cam disc displaced radially relative to one another, act on the similarly constructed contact sets installed at opposite plate edges.

10. A programme switch, comprising at least one cam disc capable of being disengaged from the driving means by means of an axial displacement of the cam shaft, wherein the cam disc can be turned forwards in the disengaged condition in the normal direction of rotary operation, the forward rotation of the disengaged cam disc or cam shaft being limited by means of a spring-loaded abutment, an initial condition for the said cam disc, the abutment stopping the cam disc in its initial condition and the abutment being released by means of the axial movement of the cam shaft to the engagement of the cam disc with its driving means and goes into an inoperative condition under spring action and permits an advance of the cam disc from its initial condition in engaged or disengaged condition.

11. A programme switch comprising at least one control cam disc acting on switch contacts, an axially displaceable cam shaft, a fixed switch portion, a lever pivoted on the said fixed switch portion, a forward switch pawl attached to the said lever, stop means attached to the said fixed switch portion, a step switch gear wheel operatively associated with the said forward switch pawl, spring means continuously acting onto the said lever thereby tending to maintain the said lever and forward switch pawl in a normal position in which the forward switch pawl is engaged between the said stop means and the said step switch gear wheel thereby preventing forward advance of the step switch gear wheel, an axial rest position and an axial disengaging position for the said cam shaft and adisengaged position for the said lever, means on the cam shaft operatively associated with the said lever for engaging the said lever and shifting it to its said disengaged position thereby disengaging the said forward switch pawl from its normal position to a disengaged position when the said cam shaft is shifted to its said disengaging position, an operating position for the said lever and the said forward switch pawl, and driving means comprising means for periodically shifting the said lever to its operating position for periodically advancing the saidstep switch gear wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,240,140 Henderson Sept. 11, 1917 1,444,557 Sachs Feb. 6, 1923 1,659,422 Bachtold Feb. 14, 1928 2,416,739 Chandler Mar. 4, 1947 FOREIGN PATENTS 386,746 Great Britain Jan. 26, 1933 

